Origin of the eukaryotic nucleus determined by rate-invariant analysis of rRNA sequences

The origin of the eukaryotic nucleus is difficult to reconstruct. Eukaryotic organelles (chloroplast, mitochondrion) are eubacterial endosymbionts, but the source of nuclear genes has been obscured by multiple nucleotide substitutions. Using evolutionary parsimony, a newly developed rate-invariant treeing algorithm, the eukaryotic ribosomal rRNA genes are shown to have evolved from the eocytes, a group of extremely thermophilic, sulphur-metabolizing, anucleate cells. The deepest bifurcation yet found separates the reconstructed tree into two taxonomic divisions. These are a proto-eukaryotic group (karyotes) and an essentially bacterial one (parkaryotes). Within the precision of the rooting procedure, the tree is not consistent with either the prokaryotic-eukaryotic or the archaebacterial-eubacterial-eukaryotic groupings. It implies that the last common ancestor of extant life, and the early ancestors of eukaryotes, probably lacked nuclei, metabolized sulphur and lived at near-boiling temperatures.     

基于mt16S rDNA的长蝽总科(异翅亚目:蝽次目)系统发育的研究

利用16S rDNA分子约540 bp的序列对长蝽总科9个科29个种进行系统发育分析.运用MP法、ML法和NJ法分析,结果表明:原来属于广义长蝽科的Pachygronthidae、Rhyparochromidae、Cymidae、Geocoridae、Blis-sidae、Oxycarenidae和狭义Lygaeidae并不形成一个单系的广义长蝽科;梭长蝽科Pachygronthidae的两个族Pachygronthini和Teracriini分成两支而形成多系;莎长蝽科Cymidae与梭长蝽科Pachygronthidae的Pachygronthi-ni族总是聚成一支形成姐妹群.研究说明广义长蝽科是多系,这与最近的形态学研究一致,从分子水平上支持Henry(1997)把广义长蝽科中的部分亚科提升为科的修订.与现有的形态分类系统有所不同的是,地长蝽科和狭义长蝽科都是多系群.     

西藏虫草属真菌生物学特性研究及其无性型rRNA基因ITS间隔区系统发育分析

研究从新鲜冬虫夏草分离得到的菌株的形态学特征,并验证其对蝙蝠蛾幼虫的侵染能力。对菌株分化的两个亚型菌株进行了生物学特性研究,并对rRNA基因ITS片段进行了系统发育分析。结果表明：①菌株在18±4℃条件下培养两周后,产生乳白色突起,里面有淡黄色孢子,这种情况下的菌体在侵染蝙蝠蛾幼虫后,20天后长出了子实体;②菌株进一步分化成无性型的两个亚型菌株CC-1和CC-3,这两株菌在表观上差异不明显,但是其分生孢子形态上有显著差异。菌株CC-1的分生孢子为线型孢子,而CC-3的分生孢子却为镰刀型孢子,两菌株均存在有性生殖和无性生殖两种生殖方式;③对无性型两菌株CC-1和CC-3的rRNA基因ITS片段的系统发育分析表明,两株菌均与冬虫夏草非常相似。     

Phylogeny and divergence time estimation of cheilostome bryozoans based on mitochodrial 16S rRNA sequences

The mitochondrial 16S rDNA sequences of 40 species of cheilostome bryozoans including those of 24 species newly determined were used to reconstruct the phylogenetic tree using neighboring-joining and maximum-parsimony methods. By applying molecular clock technique on the basis of the appropriate phylogeny and the fossil record, the divergence times of the two main cheilostome groups, Anasca and Ascophora sensu stricto, were estimated. The results show that the molecular phylogeny of the higher taxonomic groups (superfamilies and higher taxa) of cheilostome bryozoans is mostly in conflict with the morphology-based phylogenetic trees; the divergence of the extant groups of Anasca and those of Ascophora sensu stricto is estimated to have happened about 263 Ma (Permian Guadalupian Epoch) and 183 Ma (Early Jurassic), respectively.     

基于粗糙集理论的故障树重要度分析

在工程风险评价的失效可能性计算中,故障树重要度分析是一项重要技术,它经常遇到许多不确定、不完整的因素.采用粗糙集理论对这些不确定、不完整数据进行处理与分析,并通过埋地燃气管道的外腐蚀故障树重要度分析的实例,阐述了粗糙集理论的概念、原理、方法和应用.结果表明,粗糙集理论是一种完全基于客观的综合重要度分析方法,在工程上具有实用意义.     

基于模糊集理论事件树分析方法在风险分析中应用

应用事件树分析方法进行风险分析时,通常将事件的发生概率当做确定值,但是在许多工程实际中,根据历史资料确定事件发生概率是非常困难的,经常需要利用专家的知识对事件的失败概率给出模糊的评断。因此提出基于模糊集理论的事件树分析方法,将模糊性语言转换为三角模糊数或梯形模糊数,应用模糊数λ截集以及模糊数积分排序方法,对后果事件的风险进行综合评判,船舶建造过程中风险分析实例验证了该方法切实可行。     

The phylogenetic relationship of the family Lutjanidae based on analyses of AFLP and mitochondrial 12S rRNA sequences

Fishes of the family Lutjanidae are commercially important in South China Sea. However, the phylogeny of Lutjanids is still unclear and there are many controversies over it. Herein, studies about the phylogeny of Lutjanids were performed based on Amplified Fragment Length Polymorphism （AFLP） analysis of genome DNA and sequence analysis of mitochondrial 12S rRNA gene, and 10 Lutjanidae species and 1 Lethrinidae species were employed. The topologies of minimum evolution （ME） trees based on the two analyses respectively were congruent except for positions of genera Pristipomoides and Caesio. The optimal substitution model TrN ＋ G for DNA sequences of 12S rRNA genes in Lutjanids was obtained using MODELTEST 3.6 software and maximum likelihood （ML） analysis supports the topology displayed by the ME tree. The test of log-likelihood suggests that the use of molecular clock calibrations to estimate species divergence time appeared valid. Phylogenetic analyses using AFLP data and DNA sequences of mitochondrial 12S rRNA genes indicated the monophyly of Lutjanus genra. However, further studies are required to reveal the phylogenetic relationship among other genera. In addition, the results demonstrated that AFLP genetic marker was suitable for the phylogenetic analysis of Lutjanids.     

基于故障树加权的柴油机供给系统的可靠性分析

要计算故障树顶事件的概率,必须知道各个底事件的分布类型和参数估计值,由于机械元件的失效数据在过去和将来都是难以获得的,尤其在中小企业的条件下更是如此,从而使设计人员陷入困境.采用故障树加权方法,即使只知道故障树中一、二个事件的失效概率也能预测整个系统的可靠性,并通过柴油机供给系统的可靠性分析得到验证.     

基于事故树分析法的矸石山安全评价

针对煤矸石在长期堆放过程中不但会对环境造成影响,而且会直接或间接的对人身安全造成伤害,存在安全隐患的问题,应用AHP软件对矿区矸石山的危险源进行确定,采用事故树分析法对危险源进行分析,通过研究表明:应用AHP和事故树分析法能够找出矸石山存在的潜在危险,并提出预防及治理措施。将预防措施应用到实际生产中,能够提高煤矸石排放的管理能力,并能减少矸石山危险事故的发生。     

基于16S rRNA序列的鳃金龟亚科5族种类的系统发育关系

测定了鳃金龟亚科部分种类的线粒体16SrRNA部分序列,运用MEGA 4.0、PAUP*4.0b10和MrBayes等软件,对5个族29个代表种的序列变异和系统关系进行了研究.序列变异分析结果显示:绢金龟族Sericini、哦鳃金龟族Hopliini、鳃金龟族Melolonthini的族内遗传距离分别为7.7%,11.3%,10.6%,族间遗传距离在12.6%～19.2%.最大似然树(ML)和贝叶斯树(BI)结果表明,所有种类分别聚集在所属的族下,哦鳃金龟族、绢金龟族分别为单系.齿爪鳃金龟属Holotrichia、云鳃金龟属Polyphylla、胸突鳃金龟属Hoplosternus、Hilyotrogus、双绺鳃金龟属Amphimallon、Hoplochelus、婆鳃金龟属Brahmina和皱鳃金龟属Trematodes聚在鳃金龟族分支下,没有形成明显的根鳃金龟族Rhizotrogini分支.齿爪鳃金龟属的非单系性与前人研究结果一致.皱鳃金龟属Trematodes和婆鳃金龟属Brahmina的代表种为姐妹种.绢金龟族的绢金龟属Serica和玛绢金龟属Maladera多数种类聚在本属分支下.证明16SrRNA序列可探讨鳃金龟亚科高级阶元的系统发育关系.     

基于PWM扫描算法的启动子区域统计分析

为了寻找启动子区域上转录因子结合位点的分布规律,进而研究这种规律与真核基因表达调控机制之间的关系,该文从已有数据出发,运用位置权重矩阵(PWM)扫描算法对启动子区域上4种与肝脏特异表达相关的转录因子结合位点分布情况进行了初步研究,并提出了一种新的序列评分方法。通过该方法提取的统计特征,肝脏特异基因的鉴别准确率可以达93.33%。实验结果表明:肝脏特异基因的启动子区域上结合位点的分布情况与其他基因相比存在显著差异。新的序列评分方法可以更好地反映这种差异性,实现肝脏特异基因的精确鉴别。     

基于故障树分析武警运输安全人为因素

将故障树分析法应用到武警运输安全人的因素分析中,建立了武警运输安全事故树,进行了简化、定性和定量分析,计算了基本事件的重要度,并给出了一般计算公式。     

Phylogenetic investigation on five genera of tintinnid ciliates （Ciliophora, Choreotrichia）, based on the small subunit ribosomal RNA gene sequences

The phylogenetic relationship among tintinnid ciliates are relatively poorly studied based on molecular data. In the present work, seven species belonging to five genera of the order Tintinnida (Amphorellopsis acuta, Codonellopsis nipponica, Favella taraikaensis, Stenosemella nivalis, Tintinnopsis beroidea, Tintinnopsis cylindrica and Tintinnopsis lohmanni) were analyzed using the information on their small subunit ribosomal RNA gene sequences. Phylogenetic trees were constructed using Bayesian inference (BI), maximum parsimony (MP), neighbor-joining (NJ), and least-squares (LS) methods. Generally, similar topologies were revealed with high or moderate supports, in which the main results show that (1) all tintinnids analyzed belong to a single assemblage; (2) congeners in Tintinnopsis do not cluster together, which indicates that the lorica-based definition for this genus is not consistent with the SSU rRNA phylogeny; (3) A. acuta groups with Tintinnidium mucicola but not with Eutintinnus, indicating that the traditional family Tintinnidae might be a paraphyletic group; (4) Stenosemella and Codonellopsis are clearly most related and possibly even merged into one genus regarding their similar morphology and molecular analyses, and possession of a hyaline collar is the only characteristic of the genus.     

基于二叉树的族谱生成系统的设计与实现

针对历史较长的家族数据量大,普通书籍方法查阅起来困难的问题,设计一款基于二叉树的族谱自动生成管理系统,系统主要利用计算机数据结构中的二叉树,对家族的族谱进行生成及实现管理功能。实验证明,系统能有效实现族谱的自动生成,具有一定的应用性。     

基于模糊集合理论的液压缸故障树分析方法研究

文章针对汽车起重机液压缸故障,建立了一个比较完整的故障树;针对液压缸故障树分析时存在底事件故障概率获取不足的特点,将模糊集合理论和专家判断法引入故障树分析法(fault tree analysis,FTA)中,使故障树具有处理模糊信息的能力;在对故障树进行传统定性分析的基础上,将底事件发生概率的可靠性数据与通过模糊计算获得的模糊概率相结合进行故障树定量分析。结合某型号汽车起重机实例数据进行分析,估计出了故障树子树顶事件的模糊故障概率及其各底事件的重要度。     

基于调用环境树的软件度量研究

通过对调用环境树的扩展,并针对方法的类内和类间度量,在提出新的度量公式的基础上,证明了相关的度量可行性需满足的性质。     

基于Merkle树的微支付方案

针对PayWord协议在频繁更换商家的场合中执行效率不高的问题,提出了一种基于Merkle。树的微支付方案,它通过使用MerKle树将散列链连接起来,使多个散列链共用一个消费者数字签名,从而减少了公钥签名的数量,节省了计算开销,适用于消费者对多个商家进行支付。此外,还对该方案进行了扩展,将消费者在支付过程中的计算量由0(n)降低到O(n^1/2),因此方案的执行效率大大提高。     

近代图书馆的先驱是古代书院而非藏书楼

在对书院、藏书楼、学校和图书馆的本质属性与功能特征进行辨析的基础上,提出就本质而言,近现代图书馆的先驱是书院而非藏书楼,书院精神的继承发扬者是图书馆而非学校.     

用决策树改进基于协议分析的入侵检测技术

针对传统的基于简单模式匹配的入侵检测技术性能低，误报率和漏报率高的问题，提出基于决策树算法的协议分析方法，描述该算法的定义和实现，通过实验与模式匹配作性能比较，研究结果表明，基于决策树算法的协议分析方法根据协议的结构特点准确捕获入侵信号，大大提高了入侵检测系统的性能。